Here are the books that I'd reccomend:
-Current medical diagnosis and treatment: a great medical resource, not too pricey either. I like this book better then Harrison's or Cecils.
-uptodate.com: If your program doesn't subscribe to this, you might consider getting a group rate with some of colleagues. A lot of residents use this to look stuff up for management issues.
-Sanford abx guide: prob the best abx guide out there. Should be able to get a free one froma drug rep if you don't already have one.
-E-pocrates: great for meds and looking up dosages
-Washington manual or Ferris medical guide are decent pocket resources.